Oxidation of organic compounds

ABSTRACT

An improved method for treating organic compounds present in soil, groundwater and other environments is disclosed. The method involves the use of a peroxygen compound and a chelated transition metal.

FIELD OF THE INVENTION

The present invention relates to the in situ and ex situ oxidation oforganic compounds in soils, groundwater, process water and wastewaterand especially relates to the in situ oxidation of volatile andsemi-volatile organic compounds, pesticides and herbicides, and otherrecalcitrant organic compounds in soil and groundwater.

BACKGROUND OF THE INVENTION

The presence of volatile organic compounds (VOCs), semi volatile organiccompounds (SVOCs) or pesticides in subsurface soils and groundwater is awell-documented and extensive problem in industrialized andindustrializing countries. Many VOC's and SVOC's are compounds which aretoxic or carcinogenic, are often capable of moving through the soilunder the influence of gravity and serving as a source of watercontamination by dissolution into water passing through the contaminatedsoil. These include, but are not limited to, chlorinated solvents suchas trichloroethylene (TCE), vinyl chloride, tetrachloroethylene (PCE),methylene chloride, 1,2-dichloroethane, 1,1,1-trichloroethane (TCA),carbon tetrachloride, chloroform, chlorobenzenes, benzene, toluene,xylene, ethyl benzene, ethylene dibromide, methyl tertiary butyl ether,polyaromatic hydrocarbons, polychlorobiphenyls, phthalates, 1,4-dioxane,nitrosodimethyl amine, and methyl tertbutyl ether.

In many cases discharge of these compounds into the soil leads tocontamination of aquifers resulting in potential public health impactsand degradation of groundwater resources for future use. Treatment andremediation of soils contaminated with VOC or SVOC compounds have beenexpensive, require considerable time, and in many cases incomplete orunsuccessful. Treatment and remediation of volatile organic compoundsthat are either partially or completely immiscible with water (i.e., NonAqueous Phase Liquids or NAPLs) have been particularly difficult. Alsotreatment of highly soluble but biologically stable organic contaminantssuch as MTBE and 1,4-dioxane are also quite difficult with conventionalremediation technologies. This is particularly true if these compoundsare not significantly naturally degraded, either chemically orbiologically, in soil environments. NAPLs present in the subsurface canbe toxic to humans and other organisms and can slowly release dissolvedaqueous or gas phase volatile organic compounds to the groundwaterresulting in long-term (i.e., decades or longer) sources of chemicalcontamination of the subsurface. In many cases subsurface groundwatercontaminant plumes may extend hundreds to thousands of feet from thesource of the chemicals resulting in extensive contamination of thesubsurface. These chemicals may then be transported into drinking watersources, lakes, rivers, and even basements of homes throughvolatilization from groundwater.

The U.S. Environmental Protection Agency (USEPA) has established maximumconcentration limits for various hazardous compounds. Very low andstringent drinking water limits have been placed on many halogenatedorganic compounds. For example, the maximum concentration limits forsolvents such as trichloroethylene, tetrachloroethylene, and carbontetrachloride have been established at 5 .mu.g/L, while the maximumconcentration limits for chlorobenzenes, polychlorinated biphenyls(PCBs), and ethylene dibromide have been established by the USEPA at 100.mu.g/L, 0.5 .mu./L, and 0.05 mu.g/L, respectively. Meeting thesecleanup criteria is difficult, time consuming, costly, and oftenvirtually impossible using existing technologies.

U.S. Pat. No. 6,474,908 (Hoag, et al) and U.S. Pat. No. 6,019,548 (Hoaget al) teach the use of persulfate with divalent transition metal saltsfor the destruction of volatile organic compounds in soil. Adisadvantage of this technique is that upon oxidation and/or hydrolysis,the divalent metals, added as a catalyst, may undergo oxidation andprecipitation, limiting the survivability and transport of the catalyst,and hence the reactivity of the persulfate to the entire field ofcontamination.

Iron (III) has been known to catalyze the reactions of hydrogenperoxide. (Hydrogen Peroxide; Schumb, W. C.; Satterfield, C. N.; andWentworth, R. L.; Reinhold Publishing Corporation, New York, N.Y., 1955;pg 469). Iron (III) complexes used with hydrogen peroxide, have beenreported to show an ability to oxidize complex pesticides (Sun, Y andPignatello, J. J. Agr. Food. Chem, 40:322-37, 1992). However Iron (III)is a poor catalyst for the activation of persulfate.

SUMMARY OF THE INVENTION

The present invention relates to a method for the treatment ofcontaminated soil, sediment, clay, rock, and the like (hereinaftercollectively referred to as “soil”) containing volatile organiccompounds, semi-volatile organic compounds, pesticides and herbicides,as well as the treatment of contaminated groundwater (i.e., water foundunderground in cracks and spaces in soil, sand and rocks), process water(i.e., water resulting from various industrial processes) or wastewater(i.e., water containing domestic or industrial waste, often referred toas sewage) containing these compounds.

The method of the present invention uses one or more water solubleoxidants in combination with a chelated transition metal catalyst underconditions which enable oxidation of most, and preferably substantiallyall, the organic compounds in the soil, groundwater, process waterand/or wastewater.

The oxidant may be any solid phase, water soluble peroxygen compound,introduced into the soil or water in amounts, under conditions and in amanner which assures that the oxidizing compound is able to contact andoxidize most, and preferably substantially all, the target compounds.

The chelated transition metal catalyst may be composed of divalent ortrivalent cationic species of a transition metal. Examples include, butare not limited to, iron, copper, manganese, nickel, chromium, vanadium,silver and zinc. The transition metals can be complexed by a variety ofchelants that are known in the literature. Examples of suitable chelantsinclude, but are not limited to; ethylenediaminetetraacetic acid (EDTA),hydroxyacetic acid, phthalate, phosphate, pyrophosphate, metaphosphate,1,2-benzenediol, citrate, nitriloacetic acid, tetrahydroxy-1,4-quionone,1,2-dihydroxynaphthalene, hydroxyethylene diphosphonic acid, maleate,ascorbate, and aspartate. By complexing the transition metal catalystwith a chelant, it has been found that the survivability of the catalystis greatly enhanced, and also that trivalent transition metal cationsmay be used. As indicated above, in the absence of a chelant, divalentmetal cations are converted to trivalent cations which react in thepresence of water or carbonate to form insoluble hydroxides orcarbonates which precipitate out and/or do not move in the soil with theoxidant thus resulting in the decrease of catalytic activity. Alsowithout the presence of a chelant some trivalent metal cations are noteffective catalysts

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the process of the present invention, organiccompounds are oxidized by contacting the organic compound with acomposition comprising (a) a water soluble peroxygen compound and (b) achelated divalent or trivalent transition metal.

In one embodiment of the invention, the oxidation of organic compoundsat a contaminated site is accomplished by the injection of a combinationof a persulfate and a chelated transition metal catalyst into the soil.

In a preferred form of the invention, sodium persulfate (Na.sub.2S.sub.2 O.sub.8) is introduced into the soil.

For in situ soil treatment, injection rates must be chosen based uponthe hydrogeologic conditions, that is, the ability of the oxidizingsolution to displace, mix and disperse with existing groundwater andmove through the soil. Additionally, injection rates must be sufficientto satisfy the soil oxidant demand and chemical oxidant demand in arealistic time frame and to compensate for any decomposition of theoxidant. It is advantageous to clean up sites in both a cost effectiveand timely manner. Careful evaluation of site parameters is crucial. Itis well known that soil permeability may change rapidly both as afunction of depth and lateral dimension. Therefore, injection welllocations are also site specific. Proper application of any remediationtechnology depends upon knowledge of the subsurface conditions, bothchemical and physical, and the present process is not different in thatrespect.

While sodium persulfate is the preferred peroxygen compound foroxidizing soil constituents in accordance with the present invention,other solid phase water soluble peroxygen compounds can be used. By“solid phase water soluble peroxygen compound” it is meant a compoundthat is solid and water soluble at room temperature and contains abi-atomic oxygen group, O—O. Such compounds include all thedipersulfates, monopersulfates, peroxides, and the like, with thedipersulfates being preferred because they are inexpensive and survivefor long periods in groundwater saturated soil under typical siteconditions.

The most preferred dipersulfate is sodium persulfate as it has thegreatest solubility in water and is least expensive. Moreover, itgenerates sodium and sulfate upon reduction, both of which arerelatively benign from environmental and health perspectives. Potassiumpersulfate and ammonium persulfate are examples of other persulfateswhich might be used. Potassium persulfate, however, is an order ofmagnitude less soluble in water than sodium persulfate; and ammoniumpersulfate is even less desirable as it may decompose into constituentssuch as ammonium ion which are potential health concerns.

The most preferred transition metal is iron, which can be used in eitherthe divalent or trivalent state, as it is inexpensive, common to groundsoils, and has low toxicity. The most preferred chelating agent isethylene diamine tetraacetic acid (EDTA), However, any complexing agent,chelant or sequesterant common in the literature may be used. Thechelant may be either an organic (carbon based) or inorganic compound(i.e., phosphates), or it may be a combination of inorganic and organicmoieties such as organophosphates. Examples include but are not limitedto: hydroxyacetic acid, phthalate, phosphate, pyrophosphate,metaphosphate, 1,2-benzenediol, citrate, nitriloacetic acid,tetrahydroxy-1,4-quionone, 1,2-dihydroxynaphthalene, hydroxyethylenediphosphonic acid, maleate, ascorbate, and aspartate. The chelant isadded in sufficient quantity to insure at minimum complete complexationof the transition metal. Overdosing the chelant is not desirable as theexcess chelant may increase the oxidant demand.

The preferred valence state of iron is the trivalent state as it isstable and does not require special handling. Divalent iron compoundsare easily oxidized by ambient oxygen.

The chelant and the transition metal salt may be mixed together, shippedand stored prior to being combined with water in the same vessel andthen injected. The peroxygen compound and chelant-metal combinationlikewise, may be mixed together and shipped or stored prior to beingcombined with water in the same vessel prior to injection. Solutions ofthe peroxygen compound and the chelated metal catalyst can be injectedsimultaneously or sequentially. If injected sequentially, it ispreferable that the chelated metal catalyst is injected first. It isalso preferred that enough peroxygen compound be injected as to satisfythe soil oxidant demand, compensate for any decomposition and oxidizeand destroy the majority if not all of the organic compounds.

Depending upon the type of soil, target compounds, and other oxidantdemand at the site, the concentrations of peroxygen compound used in thepresent invention may vary from 0.5 mg/L to greater than 250,000 mg/L.The preferred concentrations are a function of the soil characteristics,including the site-specific oxidant demands. Hydrogeologic conditionsgovern the rate of movement of the chemicals through the soil, and thoseconditions must be considered together with the soil chemistry tounderstand how best to perform the injection. The techniques for makingthese determinations and performing the injections are well known in theart. For example, wells or borings can be drilled at various locationsin and around the suspected contaminated site to determine, as closelyas possible, where the contamination is located. Core samples can bewithdrawn, being careful to protect the samples from atmosphericoxidation. The samples can then be used to determine soil oxidantdemand, chemical (e.g. VOC) oxidant demand and the oxidant stabilityexisting in the subsurface. The precise chemical compounds in the soiland their concentration can be determined. Contaminated groundwater canbe collected. Oxidants can be added to the collected groundwater duringlaboratory treatability experiments to determine which compounds aredestroyed, in what order and to what degree, in the groundwater. It canthen be determined whether the same oxidants are able to destroy thosechemicals in the soil environment.

One method for calculating the preferred amount of peroxygen compound tobe used per unit soil mass (for an identified volume of soil at thesite) is to first determine the minimum amount of peroxygen compoundneeded to fully satisfy soil oxidant demand per unit mass ofuncontaminated soil. A contaminated soil sample from the identifiedvolume of soil is then treated with that predetermined (per unit mass)amount of peroxygen compound; and the minimum amount of peroxygencompound required to eliminate the organic compounds in that treatedsample is then determined. Chemical reaction stoichiometry governs themass/mass ratios and thus the total amount required to achieve thedesired result. In actuality the amount of peroxygen compound injectedinto various locations at a single contaminated site will vary dependingupon what is learned from the core samples and other techniques formapping what is believed to be the subsurface conditions.

The goal is for the concentration of peroxygen compound in the injectedsolution to be just enough to result in the peroxygen compound reactionfront traveling throughout the area of contamination requiring treatmentin sufficient quantity to oxidize the contaminants present. (Thesaturated soil zone is the zone of soil which lies below the water tableand is fully saturated. This is the region in which groundwater existsand flows.) In certain saturated zones where the natural velocity of thegroundwater is too slow for the purposes of treatment within a certaintimeframe, the velocity of groundwater can be increased by increasingthe flow rate of the injected persulfate solution or installation ofgroundwater extraction wells to direct the flow of the injectedperoxygen compound solution. Certain soils to be treated may be inunsaturated zones and the method of peroxygen compound injection may bebased on infiltration or trickling of the peroxygen compound solutioninto the subsurface to provide sufficient contact of the soils with theinjected chemicals. Certain soils and conditions will require largeamounts of peroxygen compound to destroy soil oxidant demand, whileother soils and conditions might not. For example, sandy soils havinglarge grain size might have very little surface area, very littleoxidizable compounds and therefore very little soil oxidant demand. Onthe other hand, silty or clayey soils, which are very fine grained,would have large surface area per unit volume. They are likely to alsocontain larger amounts of oxidizable compounds, and also may cause agreater degree of decomposition of the peroxygen compound and thus havea higher overall soil oxidant demand.

The concentrations of the chelated transition metal catalyst used in thepresent invention may vary from 1 to 1000 ppm on a metal cation basis.

In addition to in situ applications the process may also be employed exsitu. In addition to soil it may be used to treat sludges, sands, tars,groundwater, wastewater, process water or industrial water.

In order to describe the invention in more detail, the followingexamples are set forth:

EXAMPLE 1 Study Demonstrating Efficacy of Fe(III)-EDTA and SodiumPersulfate

Solid sodium persulfate (3.95 grams) and transition metal (Fe(II) orFe-EDTA) were added to 40 mL brown glass vials to obtain targetedconcentrations.

Distilled water was added to the vial to contain zero headspace and thevial was capped with a teflon lined silicon rubber screw top to preventloss of volatile organic compounds.

A mixture of the volatile organic compounds (VOC) (in methanol) wasinjected through the septum of the sealed vials into thewater/oxidant/metal mixture.

Controls were constructed, without the addition of sodium persulfate.

All vials were stored at room temperature for 7 days.

Following 7 day reaction period, vials were stored at 4 deg C. foranalysis.

Analyses were performed on a gas chromatograph/mass spectrometerutilizing USEPA SW-846, Method 8260B

Reaction data were compared to control data in order to factor out anynon-oxidative (i.e., volatile) losses that may have occurred

The results are shown in the following table after 7 days of reaction:Percent Reduction Relative to Control (VOC) Fe(II) Fe (III) Fe-EDTA1,1-DCE 100 96 100 MTBE 85.4 33 50.7 cis-DCE 100 52 100 Benzene 100 7899 TCE 100 57 100 PCE 100 47 100 Toluene 100 100 100 Chlorobenzene 10074 100

This study demonstrates the ability of chelated trivalent iron toeffectively destroy a variety of contaminant compounds.

EXAMPLE II Study Demonstrating Effectiveness of Differing Chelants

Sodium persulfate was dissolved into distilled water to achieve a 10%w/v concentration. The persulfate solution was added to 20 mL volatileorganic analysis (VOA) vials.

FeCl₃ was added to achieve a final concentration of 10 mM (550 mg Fe/L)into the vials targeted for the Fe(III) study. For comparison to Fe(II)with persulfate, FeSO₄ was added to achieve a final concentration of 9mM (500 mg Fe/L) to the appropriate vials.

The following chelants were used. Cat Catechol (1,2- benzenediol) 0.92%w/v PhTh Potassium hydrogen phthalate 1.54% w/v DHNAH1,2-dihyroxynaphthalene 1.54% w/v NTA nitriloacetic acid 1/61% w/v + 685uL 30% NaOH THQ tetrahydroxy-1,4-quionone 1.45% w/v + 450 uL 30% NaOHEDTA ethylenediaminetetraacetic acid 3.57% w/v GLY hydroxyacetic acid0.94% w/v

Distilled water was added to the vial to contain zero headspace and thevial was capped with a teflon lined silicon rubber screw top to preventvolatile loss

A mixture of the volatile organic compounds (in methanol) was injectedthrough the septum of the sealed vials into the water/oxidant/metalmixture. Controls identical to the reaction vials were constructed, onewith the addition of sodium persulfate alone and one with sodiumpersulfate and an unchelated iron (II) sulfate.

All vials were stored at room temperature. Analyses were conducted after7, 14 and 21 days. Analyses were performed on a gas chromatograph/massspectrometer utilizing USEPA SW-846, Method 8260B.

The results with various organic compounds are shown in the followingtables: Carbon Tetracloride: Elapsed Persulfate + Persulfate +Persulfate + Persulfate + Persulfate + Persulfate + Time, Persulfate +Persulfate + Persulfate + Fe(III) + Fe(III) + Fe(III) + Fe(III) +Fe(III) + Fe(III) + days Persulfate Fe(II) Fe(III) Fe(III) + Cat DHNAHTHQ EDTA GLY NTA PhTh 0 11,000 11,000 11,000 11,000 11,000 11,000 11,00011,000 11,000 11,000 7 12,000 11,000 12,000 11,000 9,400 9,400 9,80012,000 11,000 12,000 14 12,000 11,000 12,000 12,000 9,300 9,400 5,30011,000 11,000 12,000 21 11,000 10,000 12,000 12,000 9,300 8,400 5,0009,800 11,000 13,000

Methyl-t-Butyl ether Elapsed Persulfate + Persulfate + Persulfate +Persulfate + Persulfate + Persulfate + Time, Persulfate + Persulfate +Persulfate + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) +days Persulfate Fe(II) Fe(III) Fe(III) + Cat DHNAH THQ EDTA GLY NTA PhTh0 13,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 13,0007 13,000 1,900 11,000 11,000 8,300 690 6,400 8,500 12,000 12,000 1413,000 0 7,000 10,000 6,000 170 440 3,900 9,600 11,000 21 13,000 0 4,6009,900 4,700 0 250 1,500 3,900 11,000

t-Butyl Alcohol Elapsed Persulfate + Persulfate + Persulfate +Persulfate + Persulfate + Persulfate + Time, Persulfate + Persulfate +Persulfate + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) +days Persulfate Fe(II) Fe(III) Fe(III) + Cat DHNAH THQ EDTA GLY NTA PhTh0 15,000 15,000 15,000 15,000 15,000 15,000 15,000 15,000 15,000 15,0007 15,000 11,000 15.000 15,000 15,000 3,800 15,000 15,000 17,000 16,00014 16,000 1,100 14,000 18,000 12,000 1,700 3,600 13,000 15,000 15,000 2114,000 830 13,000 11,000 14,000 1,600 3,300 8,900 8,900 20,000

Benzene Elapsed Persulfate + Persulfate + Persulfate + Persulfate +Persulfate + Persulfate + Time, Persulfate + Persulfate + Persulfate +Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + daysPersulfate Fe(II) Fe(III) Fe(III) + Cat DHNAH THQ EDTA GLY NTA PhTh 013,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 77,000 0 1,600 880 0 0 160 0 2,800 3400 14 2,800 0 0 380 0 0 0 0 2401,300 21 940 0 0 200 0 0 0 0 0 690

Ethylbenzene Elapsed Persulfate + Persulfate + Persulfate + Persulfate +Persulfate + Persulfate + Time, Persulfate + Persulfate + Persulfate +Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + daysPersulfate Fe(II) Fe(III) Fe(III) + Cat DHNAH THQ EDTA GLY NTA PhTh 013,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 75,600 0 0 0 0 0 0 0 0 0 14 1,300 0 0 0 0 0 0 0 0 0 21 240 0 0 0 0 0 0 00 0

Toluene Elapsed Persulfate + Persulfate + Persulfate + Persulfate +Persulfate + Persulfate + Time, Persulfate + Persulfate + Persulfate +Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + daysPersulfate Fe(II) Fe(III) Fe(III) + Cat DHNAH THQ EDTA GLY NTA PhTh 013,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 13,000 75,000 0 0 0 0 0 0 0 0 0 14 1,100 0 0 0 0 0 0 0 0 0 21 190 0 0 0 0 0 0 00 0

m,p-Xylene Elapsed Persulfate + Persulfate + Persulfate + Persulfate +Persulfate + Persulfate + Time, Persulfate + Persulfate + Persulfate +Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + daysPersulfate Fe(II) Fe(III) Fe(III) + Cat DHNAH THQ EDTA GLY NTA PhTh 07,800 7,800 7,800 7,800 7,800 7,800 7,800 7,800 7,800 7,800 7 2,600 0 00 0 0 0 0 0 0 14 400 0 0 0 0 0 0 0 0 0 21 0 0 0 0 0 0 0 0 0 0

Chlorobenzene Elapsed Persulfate + Persulfate + Persulfate +Persulfate + Persulfate + Persulfate + Time, Persulfate + Persulfate +Persulfate + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) +days Persulfate Fe(II) Fe(III) Fe(III) + Cat DHNAH THQ EDTA GLY NTA PhTh0 11,000 11,000 11,000 11,000 11,000 11,000 11,000 11,000 11,000 11,0007 7,100 0 2,000 1,200 310 0 0 0 3,100 4,100 14 3,100 0 0 550 180 0 0 0350 2,100 21 1,300 0 0 290 0 0 0 0 0 1,100

1,2-Dichlorobenzene Elapsed Persulfate + Persulfate + Persulfate +Persulfate + Persulfate + Persulfate + Time, Persulfate + Persulfate +Persulfate + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) +days Persulfate Fe(II) Fe(III) Fe(III) + Cat DHNAH THQ EDTA GLY NTA PhTh0 12,000 12,000 12,000 12000 12,000 12,000 12,000 12,000 12,000 12,000 78,900 0 7,600 4,100 1,400 610 3,500 3,900 8,300 7,200 14 5,300 0 3,0003,300 1,200 0 180 880 5,700 6,100 21 3,400 0 880 2,600 1,100 0 110 190380 5,000

1,3-Dichlorobenzene Elapsed Persulfate + Persulfate + Persulfate +Persulfate + Persulfate + Persulfate + Time, Persulfate + Persulfate +Persulfate + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) + Fe(III) +days Persulfate Fe(II) Fe(III) Fe(III) + Cat DHNAH THQ EDTA GLY NTA PhTh0 12,000 12,000 12,000 12,000 12,000 12,000 12,000 12,000 12,000 12,0007 8,300 0 6,700 3,000 1,300 0 1,400 2,500 7,400 6,000 14 4,200 0 2,4002,100 1,000 0 0 330 4,400 4,100 21 2,800 0 620 1,400 940 0 0 0 320 2,500

Persulfate + 1,2,4-Trichlorobenzene Persulfate + Persulfate +Persulfate + Fe(III) + Elpased Time, days Persulfate Fe(II) Fe(III)Fe(III) + Cat DHNAH 0 9,100 9,100 9,100 9,100 9,100 7 5,800 0 5,3004,000 280 14 3.100 0 3,200 3,500 250 21 1,800 0 1,600 2,900 240Persulfate + Persulfate + Persulfate + Persulfate + Persulfate +Fe(III) + THQ Fe(III) + EDTA Fe(III) + GLY Fe(III) + NTA Fe(III) + PhTh9,100 9,100 9,100 9,100 9,100 690 3,100 3,900 5,600 4,100 250 250 1,7004,300 3,400 170 250 570 1,600 2,700

Persulfate + 1,1-Dichloroethene Persulfate + Persulfate + Persulfate +Fe(III) + Elpased Time, days Persulfate Fe(II) Fe(III) Fe(III) + CatDHNAH 0 9,700 9,700 9,700 9,700 9,700 7 5,700 0 0 0 0 14 2,400 0 0 0 021 1,000 0 0 0 0 Persulfate + Persulfate + Persulfate + Persulfate +Persulfate + Fe(III) + THQ Fe(III) + EDTA Fe(III) + GLY Fe(III) + NTAFe(III) + PhTh 9,700 9,700 9,700 9,700 9,700 0 0 0 0 0 0 0 0 0 0 0 0 0 00

Persulfate + cis-1,2,Dichloroethene Persulfate + Persulfate +Persulfate + Fe(III) + Elpased Time, days Persulfate Fe(II) Fe(III)Fe(III) + Cat DHNAH 0 10,000 10.000 10,000 10,000 10,000 7 8,200 0 1,5001,400 130 14 5,200 0 0 640 0 21 3,600 0 0 320 0 Persulfate +Persulfate + Persulfate + Persulfate + Persulfate + Fe(III) + THQFe(III) + EDTA Fe(III) + GLY Fe(III) + NTA Fe(III) + PhTh 10,000 10,00010,000 10,000 10,000 0 0 0 2,100 3,100 0 0 0 540 1,700 0 0 0 0 700

Persulfate + trans-1,2-Dichloroethene Persulfate + Persulfate +Persulfate + Fe(III) + Elpased Time, days Persulfate Fe(II) Fe(III)Fe(III) + Cat DHNAH 0 2,400 2,400 2,400 2,400 2,400 7 1,700 0 390 350 014 860 0 0 160 0 21 530 0 0 0 0 Persulfate + Persulfate + Persulfate +Persulfate + Persulfate + Fe(III) + THQ Fe(III) + EDTA Fe(III) + GLYFe(III) + NTA Fe(III) + PhTh 2,400 2,400 2,400 2,400 2,400 0 0 0 560 6700 0 0 130 290 0 0 0 0 120

Persulfate + Trichloroethene Persulfate + Persulfate + Persulfate +Fe(III) + Elpased Time, days Persulfate Fe(II) Fe(III) Fe(III) + CatDHNAH 0 11,000 11,000 11,000 11,000 11,000 7 7,700 0 2,000 1,600 240 144,000 0 110 730 110 21 2,400 0 0 350 0 Persulfate + Persulfate +Persulfate + Persulfate + Persulfate + Fe(III) + THQ Fe(III) + EDTAFe(III) + GLY Fe(III) + NTA Fe(III) + PhTh 11,000 11,000 11,000 11,00011,000 100 0 150 3,200 3,100 0 0 0 550 1,100 0 0 0 0 360

Persulfate + Tetrachloroethene Persulfate + Persulfate + Persulfate +Fe(III) + Elpased Time, days Persulfate Fe(II) Fe(III) Fe(III) + CatDHNAH 0 11,000 11,000 11,000 11,000 11,000 7 7,600 0 6,900 3,700 2,70014 3,500 0 2,600 2,600 2,500 21 2,300 0 660 1,700 1,700 Persulfate +Persulfate + Persulfate + Persulfate + Persulfate + Fe(III) + THQFe(III) + EDTA Fe(III) + GLY Fe(III) + NTA Fe(III) + PhTh 11,000 11,00011,000 11,000 11,000 300 2,900 3,600 6,900 6,600 150 140 570 5,100 5,500110 0 0 260 3,700

1,4-Dioxane Elpased Time, Persulfate + Persulfate + Persulfate +Persulfate + days Persulfate Fe(II) Fe(III) Fe(III) + Cat Fe(III) +DHNAH 0 19.000 19,000 19,000 19,000 19,000 7 17,000 0 9,600 10,000 3,90014 14,000 0 2,100 8,400 1,500 21 17,000 0 0 7,800 0 Persulfate +Persulfate + Persulfate + Persulfate + Persulfate + Fe(III) + THQFe(III) + EDTA Fe(III) + GLY Fe(III) + NTA Fe(III) + PhTh 19,000 19,00019,000 19,000 19,000 0 0 2,200 8,800 12,000 0 0 0 8,300 7,300 0 0 0 07,200

Persulfate + 4-Methyl-2-Pentanone Persulfate + Persulfate + Persulfate +Fe(III) + Elpased Time, days Persulfate Fe(II) Fe(III) Fe(III) + CatDHNAH 0 14,000 14,000 14,000 14,000 14000 7 13,000 880 11,000 11,0007,000 14 14,000 0 5,000 12,000 4,200 21 14,000 250 2,000 9,000 2,600Persulfate + Persulfate + Persulfate + Persulfate + Persulfate +Fe(III) + THQ Fe(III) + EDTA Fe(III) + GLY Fe(III) + NTA Fe(III) + PhTh14,000 14,000 14,000 14,000 14,000 150 4,600 6,700 13,000 11,000 0 1702,200 9,400 9,700 0 0 410 1,600 7,100

This study demonstrates the ability of chelated iron to effectivelydestroy a variety of contaminants.

EXAMPLE III Study Demonstrating the Effects of Catalyst Dosage atElevated pH

The study was conducted in VOA 40 mL vials. The vials were dosed with astock contaminant mixture made up in methanol consisting of chlorinatedethenes, aromatics, and other compounds (see table below), toapproximately 10,000 ppm. To each vial was added 3.95 g of sodiumpersulfate, representing a 2× stoichiometric dose, including theavailable methanol.

Fe(III)-EDTA was added to each vial to achieve either a 100 mg/L or a500 mg/L concentration of iron, except for control vials, whichcontained neither persulfate nor catalyst.

The pH was adjusted to approximately 9 with sodium carbonate.

All vials were stored at room temperature for 7 days.

Following the 7 day reaction period, the vials were stored at 4 deg C.for analysis.

Analyses were performed on a gas chromatograph/mass spectrometerutilizing USEPA SW-846, Method 8260B

Reaction data were compared to data on the control vials in order tofactor out any non-oxidative (i.e., volatile) losses that may haveoccurred Fe-EDTA mg/L Fe 100 500 % decomposition after 7 days VC 99 991,1-DCE 99 99 MTBE 92 49 hexane 98 98 c12-DCE 99 99 chloroform 51 101,1,1-TCA 42 19 Benzene 99 99 TCE 99 99 toluene 99 99 PCE 99 99chlorobenzene 99 99 total VOC's 87 74 total ethenes 99 99 totalaromatics 99 99

The data demonstrates that for ethenes and aromatics, the degree ofcontaminant degradation is insensitive to the level of catalyst added.However, for several of the VOC's, an increase in catalyst is actuallydetrimental to the elimination of the VOC, indicating that the level ofcatalyst needs to be selected for the particular VOC or VOC mixture tobe treated.

EXAMPLE IV Comparison of the Long Term Effectiveness of Iron II andFe-EDTA in a Soil Environment

Iron II salts lose their effectiveness in a soil environment due totheir oxidation to iron III and the subsequent precipitation of iron IIIas an insoluble hydroxide or carbonate. One of the advantages of usingchelated iron III complexes (such as Fe-EDTA) is that they are 1)already oxidized and 2) will remain soluble over a wide pH range. Thuschelated iron III complexes potentially will transport with persulfateand continue to function as an activator.

A series of experiments were conducted to compare the long-termeffectiveness of different activators. A 40% soil water slurry was dosedwith persulfate (1 gram/250 ml of water) and different activators. Itwas dosed with a mixture of 1,4-Dioxane, ter-butyl alcohol and MTBE.Both the persulfate and the contaminant mixture were redosedperiodically. The water phase was analyzed periodically for the VOCs.The data was then plotted as a cumulative % degradation of the VOCs. Thefollowing table gives the results.

The water phase in the Fe II reaction started out as an orange color.Within 1 week it was clear. This is an indication that the iron II wasoxidized and precipitated. By comparison the Fe-EDTA supernatantremained light orange over the course of the experiment.

As can be seen from the table the activity of Fe II decreases with time.After about 4 weeks the activity is flat. After 4 weeks most of the lossin total VOC (TVOC)s in the Fe II experiment can be attributed to theslow reaction of persulfate by itself. By contrast the Fe EDTAexperiment shows a continual increase in TVOC oxidation. Week 1* Week 3Week 5* Week 7 Week 8 Ter-Butyl Alchohol, mg/L Control 11 37 35 55 57 NoFe 12 35 31 45 37 Fe II 13 30 29 43 54 Fe EDTA 12 37 25 38 25 1,4-Dioxane, mg/L Control 14 31 32 52 50 No Fe 13 27 34 38 35 Fe II 8 17 2022 16 Fe EDTA 11 15 4.2 0 0 MTBE, mg/L Control 6.7 24 29 35 39 No Fe 6.420 18 29 26 Fe II 6.9 13 3.8 7.8 4 Fe EDTA 7 15 4.2 0 0 TVOC, mg/LControl 31.7 92 96 142 146 No Fe 31.4 82 83 112 98 Fe II 27.9 60 52.872.8 74 Fe EDTA 30 67 33.4 38 25 % Change TVOC No Fe 0.9 10.9 13.5 21.132.9 Fe II 12.0 34.8 45.0 48.7 49.3 Fe EDTA 5.4 27.2 65.2 73.2 82.9*VOCs & Persulfate redosed

EXAMPLE V Comparison of Iron Availability in Soil

Solutions of persulfate (500 mg/liter of water) and iron (Fe II andFe-EDTA) were injected into a soil matrix at two separate sites. Theconcentration of the iron was then measured in monitoring wells at adistance downgradient of the injection well. The following table showsthat un-chelated divalent iron does not transport from the point ofinjection, while chelated iron does. Initial Concentration as Distancefrom Concetration of Iron Catalyst Fe, mg/L injection point, m iron,mg/L as Fe Ferrous Sulfate 187 1.5 0.287 (divalent iron - unchelated)Fe-EDTA 100 5 75-100¹¹Estimated based on color observed

1. A method of oxidizing an organic compound said method comprisingcontacting the organic compound with a composition comprising a watersoluble peroxygen compound, a source of divalent or trivalent transitionmetal ions, and a chelating agent for said metal ions.
 2. A method as inclaim 1, wherein the organic compound is present in soil, groundwater,process water or wastewater.
 3. A method as in claim 1, wherein theorganic compound is selected from the group consisting of volatileorganic compounds, semi-volatile organic compounds, polyaromatichydrocarbons, polychlorobiphenyls, pesticides and herbicides.
 4. Themethod as in claim 1, wherein the peroxygen compound is a dipersulfate.5. The method as in claim 4, wherein the dipersulfate is selected fromsodium, potassium or ammonium persulfate or a combination thereof. 6.The method as in claim 1, wherein the peroxygen compound is amonopersulfate.
 7. The method as in claim 6, wherein the monopersulfateis selected from sodium and potassium monopersulfate.
 8. The method asin claim 1, wherein the peroxygen compound is a combination of adipersulfate and monopersulfate.
 9. The method as in claim 1, whereinthe transition metal is iron.
 10. The method as in claim 9, wherein theiron is divalent.
 11. The method as in claim 9, wherein the iron istrivalent.
 12. The method as in claim 1, wherein the chelating agent isethylenediaminetetraacetic acid.
 13. The method as in claim 1, whereinthe amount of chelating agent is equal to at least the stoichiometricamount to chelate all of the transition metal.
 14. The method as inclaim 1, wherein the amount of chelated transition metal is sufficientto deliver an equivalent amount of transition metal in the range of1-1000 ppm.
 15. The method as in claim 1, wherein the amount ofperoxygen compound is sufficient to satisfy the, soil oxidant demand andto oxidize substantially all of the organic compound.
 16. The method asin claim 1, wherein the chelating agent, transition metal and theperoxygen compound are added in combination.
 17. The method as in claim1, wherein the chelating agent, transition metal and the peroxygencompound are added sequentially.